Apparatus for making bifocal lenses.



H. E. MENDELSSOHN. APPARATUS FOR MAKING BIPOGAL LENSES.

Patented Feb. 3, 1914.

APPLICATION FILED JAN. 29, 1913.

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APARATUS FOR MAKING BIFOCAL'LENEiES.

bpecification of Letters Patent.

Patented Feb. 3, 3914.

Application filed January 29, 1913. Serial No. 744,855.

To all whom it may concern Be it known that I, HERMAN E. MEN- nn'LssoHN,a citizen of Great Britain, residing at New York city, county and Stateof New York, have invented a new and Improved Apparatus for MakingBifocal Lenses, of which the following is a specification.

During the iminufacture of bifocallenses, a smaller glass .disk issuperposed upon a larger disk and fused thereto in a mui'lle. During thefusing operation, means should be provided for permitting the freeescape of the heated air from the space between the disks, so as toprevent the formation of objectionable bubbles.

My invention contemplates novel and ctlicient means for so spacing thedisks that a free escape of the air can take place, the spacing meansbeing so constituted as to securely clamp the low disk in positionwithout regard to the thickness of such disk, and lo be freelyaccessible to the hand.

In the accompanying drawing: Figure 1 is a plan of an apparatusembodying my invention, showing the two glass disks in position; Fig. 2is a longitudinal section of the apparatus without the disks; Figs. 3,4, 5 and 6 are side views partly in section showing the position of theparts during (.OHSCKIF tire stages of manufacture, and Fig. 7 a sectionthrough the finished bifocal lens.

The apparatus comprises essentially a base plate 10 from which extendsupwardly a fixed screw stem 11. This stem is shown to be securedto'plate 10 by means of an upper flange 12, and a lowercountersunk nut13, engaging opposite sides of the Upon stem 11, there is free to travela barrel 14- having an axial bore which is tapped to engage the threadof the stem. Barrel t my be made of cylindrical form and is ided with alower circumferentialfiange wl. 'ch extends in a lateral directionentirely around the barrel, said flange being preferably made continuousand constitut ing the spacing means proper. In addition to the lowerflange 15, barrel 14: is provided with an upper flange 16 constituting afinger piece by means of which the barrel may be rdtated and thus raisedand lowered along the stern.

In use, the larger and thicker disk 18, made preferablyof crown orcomparatively hard glass and provided with a ground depression 19, isplaced upon base plate 10,-

plate.

lso as to project. partly beneath barrel 14. The latter is then turnedto descend along the stem, and thus tightly l 18 against the plate 10(Fig. The l smaller and thinner disk 20 made preferably clamp the diskof flint or comparatively soft glass is then superposed upon disk 18, soas to bridge cavity 19, and rest with its edge upon flange 15 (Fig. 4)In this way, the flange will assume its function of a spacer, which willso tilt upper disk 20, as to provide air exit ports to the right andleft of that section of the flange which supports disk 20. The de vicebeing now placed in a heated muffle, disk 20 will soften and graduallysag (Fig. 5) until it becomes seated within cavity 19 and fused to disk18 (Fig. 6). During the sagging of disk 20 and its intimate union withdisk 18, the air will be free to escape from between the disks, throughthe ports formed by flange 15, as above described, so that noobjectionable air bubbles will be formed or retained between the disksand a clean connection will be obtained. After the fusing operation hasbeen completed, the compound glass disk is annealed, slipped off baseplate 10 from underneath barrel 14 and then the disk is ground to formthe bifocal lens 21 desired (Fig. 7) and thus complete the operation.

The apparatus described, will during thefusing operation not only form aspacer for the glass disks, but it will form a means for clamping thelower disk 18 tightly to the base plate 10, so that the disk is securelyheld in position. As the barrel is vertically movable along the stem,thicker or thinner the apparatus is adapted for the manufacture ofvarious kinds of lenses. Owing to the fact that the spacing flange 15entirely encircles barrel 14, an operative portion of such flange willbe projected above the lower disk to form a rest for the upper diskwithout any regard to the particular position of the barrel. That is tosay, as the barrel may require a higher or lower position upon the stemto securely clamp the lower disk, it will at all times extend a portionof its flange between the disks to form the required rest for the upperdisk[ Finally it may be stated that the barrel is freely accessible tothe hand at a convenient distance from the disks, and may thus bereadily manipulated for the interposition of the spacer.

If desired, the lower disk may be placed disks may thus be firmlyclamped, so that at a distance sidewise away from the supporting flange,in which case the upper disk is made to project laterally beyond thelower disk so as to reach above and be supported by the flange.

I claim: 4

1. An apparatus for making bifocal lenses, comprising a base plate, astem mounted thereon, a barrel movable along the stem, and disk-spacingmeans extending laterally from the barrel.

2. An apparatus for making bifocal lenses, comprising a base plate, ascrew stem mounted thereon, a threaded barrel engaging the stem, anddisk-spacing means extending laterally from the lower end of the barrel.

3. An apparatus for making bifocal lenses, comprising a base plate, ascrew stein mounted thereon, athreaded barrel engaging the stem, andprovided with a lower disk-spacing flange that extends eircumferentiallyaround the barrel.

4. An apparatus for making bifocal lenses, comprising a base plate, ascrew stem mounted thereon, a threaded barrel engaging the stem, andprovided with a lower circumferential disk-spacing flange and With anupper finger piece.

HERMAN E. MENDELSSGHN.

Witnesses:

FRANK v. BRIESEN, KATHERYNE K001i.

